Well logging is a technique used to identify characteristics of earth formations surrounding a borehole. The interrogation of a formation surrounding a borehole to identify one or more characteristics may employ sound, electrical current, electromagnetic waves, or high energy nuclear particles (e.g., gamma particles and neutrons). Receiving the interrogating particle or signal, and determining a formation property from such particle or signal, is in many cases a complex endeavor—one that is further complicated when properties of the surrounding borehole environment are unknown.
For instance, neutron wireline tools are often used to measure the capture cross sections and porosities of formations adjacent to the tools. The casing fluid within which a tool is disposed, however, can significantly skew these measurements, thereby rendering them inaccurate. Because these inaccurate measurements may then be used in any number of other production efforts, they can have significant financial and operational repercussions. If the casing fluid is properly identified, however, the measurements of a tool disposed in that casing fluid can be corrected to account for the casing fluid's effects. Accordingly, any method or system that efficiently and accurately identities the casing fluid to aid in tool correction provides a competitive advantage in the marketplace.
It should be understood, however, that the specific embodiments given in the drawings and detailed description thereto do not limit the disclosure. On the contrary, they provide the foundation for one of ordinary skill to discern the alternative forms, equivalents, and modifications that are encompassed together with one or more of the given embodiments in the scope of the appended claims.